Image processing apparatus, image processing method, and program

ABSTRACT

An image processing apparatus includes an acquisition unit configured to acquire a paper type to be used at the time of execution of an input print job, a determination unit configured to determine a paper type to be used for executing the input print job by using information about the paper type acquired by the acquisition unit, and a generation unit configured to generate a correction table corresponding to the paper type determined by the determination unit, the correction table being used to correct an image that is formed by an image forming unit by using a value obtained as a result of measuring a patch formed by the image forming unit on paper of the paper type determined by the determination unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image processing apparatus forcorrecting the color of an image that is output from a printer, an imageprocessing method therefor, and a program for generating imageprocessing parameters.

2. Description of the Related Art

With the improved performance of image forming apparatuses in recentyears, some image forming apparatuses have achieved an image qualityequivalent to that of printing machines. However, the printingcharacteristics of an image forming apparatus are known to be changed bythe influence of the installation environment. There has been a problemin that the temperature or humidity in the installation environment andthe aging of the apparatus and parts replacement change the density andtint at the time of printing, and a stable print product cannot beobtained.

To solve this problem, an image forming apparatus generally employs acalibration technique so that a stable print product is output. Thecalibration technique is a technique for correcting the gradationcharacteristics of toner used for printing. The technique prints somepatches having different gradations with known toner amounts, andmeasures the density of these patterns by using a scanner or a sensorconnected to the image forming apparatus. The technique generates acorrection look-up table (LUT) so that the result of the measurementcoincides with a known target density. Applying the generated correctionLUT at the time of printing enables obtaining a stable output suitablefor the target density characteristics.

In addition to the above-described factors of the image formingapparatus, the change in the printing characteristics is greatlyaffected by the characteristics of paper used for printing. There arevarious types of paper used for printing, which differ in size,grammage, surface property, and paper chromaticity. Even with the samecharacteristics of the image forming apparatus, different papercharacteristics (paper type) used for printing will cause differentreproduction characteristics of the result of printing. Therefore, theimage forming apparatus prepares a target value for each paper type, andperforms calibration for correcting the reproduction characteristics sothat the output value coincides with the target value, and stores acorrection LUT generated each time calibration is executed. Byperforming calibration in this way, the image forming apparatus reducesthe influence of the difference in paper (paper type) on thereproduction characteristics. In calibration, the image formingapparatus applies the correction LUT generated by using a suitabletarget value for each paper (paper type) used at the time of printing. Acombination of a specific type of paper (paper type) and a target valuecorresponding to the paper is referred to as a calibration set.

Generally, the image forming apparatus has a plurality of paper feedstages for simultaneously storing various types of paper. The pluralityof paper feed stages is able to store paper classified into differentpaper types. Suitable paper is fed according to settings at the time ofprint job execution, and then printing is performed. As described above,the paper type and the output characteristics are closely related witheach other.

Japanese Patent Application Laid-Open No. 2011-43815 discusses atechnique for presenting, at the time of calibration execution, whichpaper feed stage stores paper of a paper type to be used at the time ofcalibration execution.

However, the prior art technique determines, at the time of calibrationexecution, whether paper of a paper type involving the generation of acorrespondent correction table is stored in the apparatus, and presentswhether calibration can be executed. Therefore, a user needs to select apaper type involving the generation of a correspondent correction tablethrough the calibration execution.

Further, if calibration for generating a correction table is executed onall of paper types having a target value setting before printing, theprocessing may take a very long time. Further, if calibration isexecuted on all of paper types having a target value setting,consumables such as toner and paper may be uselessly consumed.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an image processingapparatus includes an acquisition unit configured to acquire a papertype to be used at the time of execution of an input print job, adetermination unit configured to determine a paper type to be used forexecuting the input print job by using information about the paper typeacquired by the acquisition unit, and a generation unit configured togenerate a correction table corresponding to the paper type determinedby the determination unit, the correction table being used to correct animage that is formed by an image forming unit by using a value obtainedas a result of measuring a patch formed by the image forming unit onpaper of the paper type determined by the determination unit.

According to exemplary embodiments of the present invention, it isfeasible, at the time of calibration execution, to acquire informationabout a paper type to be used for execution of an input print job, andexecute calibration on a paper type requiring the generation of acorrection LUT.

Thus, before the print job is executed, calibration can be selectivelyexecuted on a paper type requiring the generation of a correction LUT.Thus, useless consumption at the time of calibration execution can bereduced.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a connection environment of a printing systemaccording to exemplary embodiments of the present invention.

FIG. 2 illustrates a hardware module configuration of an imageprocessing apparatus according to a first exemplary embodiment.

FIG. 3 illustrates a hardware module configuration of a print serveraccording to the first exemplary embodiment.

FIG. 4 illustrates a software module configuration of the print serveraccording to the first exemplary embodiment.

FIG. 5 illustrates a software module configuration of the imageprocessing apparatus according to the first exemplary embodiment.

FIG. 6 illustrates a user interface (UI) of an adjustment/cleaningsetting screen according to the first exemplary embodiment.

FIG. 7 illustrates a UI of a paper setting screen according to the firstexemplary embodiment.

FIG. 8 illustrates a UI of a calibration paper registration screenaccording to the first exemplary embodiment.

FIG. 9 illustrates a UI of a calibration setting screen according to thefirst exemplary embodiment.

FIG. 10 illustrates a UI of a calibration execution screen according tothe first exemplary embodiment.

FIG. 11 is a flowchart illustrating processing for generating a paperfeed stage list according to the first exemplary embodiment.

FIG. 12 is a flowchart illustrating processing for generating anddisplaying a calibration execution list according to the first exemplaryembodiment.

FIG. 13 is a flowchart illustrating processing for generating acalibration execution list according to the first exemplary embodiment.

FIG. 14 is a flowchart illustrating processing for executing calibrationaccording to the first exemplary embodiment.

FIG. 15 is a flowchart illustrating procedures for executing calibrationaccording to the first exemplary embodiment.

FIGS. 16A and 16B illustrate calibration processing according to thefirst exemplary embodiment.

FIG. 17 illustrates a list of calibration sets for which calibrationcannot be executed according to a second exemplary embodiment.

FIG. 18 illustrates a UI of a calibration automatic selection settingscreen according to a third exemplary embodiment.

FIG. 19 illustrates calibration paper registration information accordingto the third exemplary embodiment.

FIG. 20 illustrates UI screen transition according to the thirdexemplary embodiment.

FIG. 21 illustrates a UI of a calibration execution list according to afourth exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

In a first exemplary embodiment, a correction table is generated, beforeperforming printing, for the type of paper (paper type) to be used atthe time of execution of an input print job. When executing a pluralityof print jobs, the present exemplary embodiment generates a calibrationtable corresponding to each paper type to be used by each of theplurality of print jobs.

FIG. 1 illustrates an example of a connection environment of a printingsystem according to the present exemplary embodiment. In the presentexemplary embodiment, an image processing apparatus 100, a print server102, and a client personal computer (PC) 103 are connected via a networkline 101. In this system, the print server 102 inputs, generates, andmanages print jobs, and sequentially transmits them to the imageprocessing apparatus 100 via the network line 101. Further, the imageprocessing apparatus 100 performs required processing on a receivedprint job, and prints it out onto actual paper. A print job is input,for example, from client PC 103 connected on the same network 101 to theprint server 102 via a print driver (not illustrated) or through a useroperation on an application graphical user interface (GUI) for the printserver 102.

FIG. 2 is a block diagram illustrating an example of a hardwareconfiguration of the image processing apparatus 100 according to thepresent exemplary embodiment. The image processing apparatus 100includes a controller unit 200 including a central processing unit (CPU)201, a scanner unit 202, an external interface (I/F) 203, an operationunit 204, a compression/decompression unit 205, a read-only memory (ROM)206, a random access memory (RAM) 207, a hard disk drive (HDD) 208, anda printer unit 209. Various control programs to be controlled by thecontroller unit 200 are stored in the ROM 206, loaded into the RAM 207as required, and controlled and executed by the CPU 201. The printerunit 209 includes an image forming unit 210, a CPU 211, a sheet feedunit 212, a sheet discharge unit 213, a measurement unit 214, and asensor 215.

FIG. 3 is a block diagram illustrating an example of a hardwareconfiguration of the print server 102 according to the present exemplaryembodiment. The print server 102 includes a controller unit 300including a CPU 301, an operation unit 302, an external I/F 303, a ROM304, a RAM 305, and an HDD 306. Various control programs to becontrolled by the controller unit 300 are stored in the ROM 304, loadedinto the RAM 305 as required, and controlled and executed by the CPU301.

FIG. 4 is a block diagram illustrating an example of a software moduleconfiguration of the print server 102 according to the present exemplaryembodiment. The following describes print processing performed by theprint server 102, with reference to FIG. 4.

A print job receiving unit 401 is processed by the CPU 301 included inthe controller unit 300. The print job receiving unit 401 receives aprint job input from the client PC 103 via the external I/F 303 or whenthe user performs an input operation on the operation unit 302, andstores the print job in the HDD 306. The HDD 306 for storing thereceived print job is referred to as a standby queue 405. The HDD 306can store a plurality of print jobs.

A print job setting unit 402 is processed by the CPU 301. The print jobsetting unit 402 performs setting required for various print processingon print jobs stored in the standby queue 405. Specifically, the printjob setting unit 402 further analyzes a print setting pre-attached tothe received print job, performs print setting specified by the user viathe operation unit 302, and stores in the standby queue 405 the printsetting as print setting information together with the print job.

A print data processing unit 403 is processed by the CPU 301. The printdata processing unit 403 reads a print job having print settings fromthe standby queue 405, performs processing according to various printsettings, and performs raster image processing (RIP) on the print job toconvert it into print data having a format printable by the imageprocessing apparatus 100. The print data processing unit 403 stores theprint data having undergone the RIP processing in the standby queue 405.

A print data transmission unit 404 is processed by the CPU 301. When theuser performs a print execution operation via the operation unit 302,the print data transmission unit 404 reads the print data stored in theHDD 306, and transmits it to the image processing apparatus 100 via theexternal I/F 303. The print data is transmitted not only at a timing ofuser operation but also at a timing of a print schedule preset by theprint job setting unit 402. Further, by specifying the plurality ofprint jobs stored in the standby queue 405, the print data transmissionunit 404 may sequentially and continuously transmit print data.

A print job information acquisition unit 406 is processed by the CPU301. The print job information acquisition unit 406 acquires print jobinformation stored in the standby queue 405, and transmits it to theimage processing apparatus 100.

FIG. 5 is a block diagram illustrating an example of a software moduleconfiguration of the image processing apparatus 100 according to thepresent exemplary embodiment. The following describes print processingperformed by the image processing apparatus 100, with reference to FIG.5.

A print data receiving unit 501 is processed by the CPU 201. The printdata receiving unit 501 receives print data transmitted from the printserver 102 via the external I/F 203, and compresses the print data viathe compression/decompression unit 205, and loads it into the RAM 207.

A bitmap data rasterization unit 502 is processed by the CPU 201. Thebitmap data rasterization unit 502 decompresses via thecompression/decompression unit 205 the print data loaded into the RAM207 to rasterize it into bitmap data. For example, color data isregularly rasterized into four different types of bitmap data (C, M, Y,and K).

A calibration correction application unit 503 is processed by the CPU201. The calibration correction application unit 503 performs correctionprocessing on the rasterized bitmap data by using the correction tablegenerated through the calibration execution. This processing absorbs andcorrects engine fluctuations to constantly provide a stable output.Calibration processing will be described in detail below.

A bitmap data processing unit 504 is processed by the CPU 201. Thebitmap data processing unit 504 converts the bitmap data correctedthrough calibration into data having a format readable by the printerunit 209. Generally, the image forming unit 210 included in the printerunit 209 is able to express a small number of gradations. Therefore, thebitmap data processing unit 504 performs what is generally calledhalf-tone processing. In half-tone processing, the number of gradationsof bitmap data is decreased to a value which can be represented by theimage forming unit 210 to enable expressing multi-gradation in a pseudoway by using the half-tone technique.

The bitmap data transmission unit 505 is processed by the CPU 201. Thebitmap data transmission unit 505 transmits the bitmap data havingundergone the half-tone processing to the printer unit 209.

The CPU 211 performs print processing on the print data transmitted tothe printer unit 209. The CPU 211 feeds paper set in the print data fromthe sheet feed unit 212, performs print processing on the paper via theimage forming unit 210, and discharges the paper from the sheetdischarge unit 213.

The following describes a workflow of the print processing assumed bythe present exemplary embodiment. The present exemplary embodimentassumes the print on demand (POD) environment. In the POD environment,much print data is regularly input from many customers, printingmanagement is performed by an administrator, and printing issequentially performed by an operator. The administrator stores manyprint jobs in the standby queue 405 of the print server 102, performsnecessary print setting, and continuously instructs print processing atone time. The operator actually performs print processing on the imageprocessing apparatus 100. For example, the operator prepares paperrequired for printing and supplies it to the sheet feed unit 212,collects print products output to the sheet discharge unit 213 andtransfers them to the following process, and executes calibration on theimage processing apparatus 100 before printing execution.

Although the printing flow of one print job is as described above, thepresent exemplary embodiment provides a workflow effective in thecalibration execution in a state where print jobs are stored in thestandby queue 405 and a printing standby state occurs in the PODenvironment.

The following describes paper setting required for executing calibrationprocessing. In paper setting, the user sets information about paperstored in the paper feed stages configured in the sheet feed unit 212.Paper setting processing is processed by the paper setting unit 510, andthen executed by the CPU 201. FIG. 7 illustrates an example of a UIscreen allowing the user to perform paper setting. The PAPER SETTINGscreen 701 is processed by the CPU 201. When the user presses a papersetting button on a main menu screen (not illustrated), the CPU 201displays the PAPER SETTING screen 701 on the operation unit 204. Theinformation displayed in this screen includes an item 702 indicatingpaper feed stages configured in the sheet feed unit 212 included in theimage processing apparatus 100, an item 703 indicating the size of paperstored in each paper feed stage, and an item 704 indicating the papertype. When the user wants to store new paper in any paper feed stage orto change existing paper to another paper, the user performs operationson the UI screen. When the user selects any paper feed stage from thepaper feed stage list 702 and then presses a SET DETAILS button 705, thescreen changes to a setting screen (not illustrated) allowing the userto set a paper size and a paper type. The paper type refers to typeinformation classified based on the grammage and surface property of thepaper preset in the image processing apparatus 100 and stored in the HDD208. At the time of print processing, the CPU 201 performs control tochange for each paper type the behavior of the image forming unit 210 atthe time of printing to provide an optimum output image quality for eachpaper type. The paper information set by the user is stored in the HDD208 and acquired by a paper feed stage information acquisition unit 511at any timing. When the user presses a RETURN button 706, the screenchanges to the main menu screen. The paper feed stage informationacquisition unit 511 is processed by the CPU 201 and the CPU 211. Thisprocessing is executed at any timing to acquire information about paperfeed stages and paper set in each paper feed stage stored in the HDD208. In the present exemplary embodiment, the calibration setting unit506 performs this processing to acquire the paper feed stageinformation.

The following describes calibration paper registration required at thetime of execution of calibration processing. Registration refers tostoring any calibration paper information in the HDD 208. Thisprocessing is processed by the calibration paper registration unit 509,and then is executed by the CPU 201. FIG. 8 illustrates an example of aUI screen for performing calibration paper registration.

When the user presses a calibration paper registration button 605 in anADJUSTMENT/CLEANING setting screen 601 (described below) or a REGISTERPAPER button 907 in a CALIBRATION SETTING screen 901, a CALIBRATIONPAPER REGISTRATION screen 801 is displayed on the operation unit 204.The CALIBRATION PAPER REGISTRATION screen 801 displays a list ofregistered paper enabling the calibration execution. Items displayed inthis list include, for example, an item 802 indicating the name ofpaper, and an item 803 indicating the date and time when the relevantpaper information was registered. In addition to the standard paper(paper type) pre-registered by the manufacturer at the time of productshipment, the user can register any paper types to be used by the user,as illustrated in the example in FIG. 8.

The pre-registered paper information includes paper types and targetvalues. A combination of a paper type and a target value is hereinafterreferred to as a calibration set. When calibration is executed on aregistered paper type by using a relevant target value, a generatedcorrection table is associated with the paper type. This correctiontable is updated each time calibration is executed.

The target value in this case is a predetermined value which is expectedto be a value output from the image forming unit 210. Calibration isexecuted so that the value output from the image forming unit 210coincides with the target value.

In the meantime, when the user presses the ADD PAPER TO BE REGISTEREDbutton 804, the screen changes to a registration reception screen (notillustrated) allowing the user to register calibration paperinformation. The calibration paper information registered includes atleast paper name information (paper type) and target information for thepaper, and is stored in the HDD 208. The target information of paperrefers to a value which is expected to be a value output from the imageforming unit 210 at the time of calibration processing. Calibration isexecuted so that the value output from the image forming unit 210coincides with the target value.

When calibration is executed on the paper type registered by the user byusing the registered target value, a generated correction table isassociated with the paper type. This correction table is updated eachtime calibration is executed.

The following describes calibration processing performed by the imageprocessing apparatus 100 according to the present exemplary embodiment.Calibration processing can be roughly classified into two pieces ofprocessing: calibration setting processing and calibration executionprocessing. The calibration setting processing can be performed at anytiming regardless of the state of the image processing apparatus 100.The calibration execution processing requires processing for printingcharts necessary for calibration and processing for updating parameterinformation necessary for the print processing. Therefore, thecalibration execution processing cannot be executed during printing of aregular print job.

The calibration setting unit 506 is executed by the CPU 201. Thecalibration setting processing is performed based on information inputby the user via the operation unit 204. FIG. 6 illustrates an example ofa UI screen for proceeding to the CALIBRATION SETTING screen 901. ThisUI screen is displayed, for example, on an operation panel which is theoperation unit 204 of the image processing apparatus 100. When the userpresses an adjustment/cleaning setting button in the main menu screen(not illustrated) on the operation unit 204, the ADJUSTMENT/CLEANINGsetting screen 601 is displayed. The ADJUSTMENT/CLEANING setting screen601 displays adjustment menu items, such as items 602 and 604 related tocalibration. When the user presses the UI button 603 in this screen, theCPU 201 displays the CALIBRATION SETTING screen 901 on the operationunit 204. Further, the item 604 is used to register information aboutpaper required to execute calibration. When the user presses thecalibration paper registration button 605, the CPU 201 displays theCALIBRATION PAPER REGISTRATION screen 801 on the operation unit 204.When the presses a UI button (RETURN button) 606 on theADJUSTMENT/CLEANING setting screen 601, the CPU 201 displays the mainmenu screen.

FIG. 9 illustrates an example of a UI screen for performing calibrationsetting according to the present exemplary embodiment. The CALIBRATIONSETTING screen 901 presents information used as a basis for determiningwhich calibration should be executed to the user, and receivescalibration settings from the user. The information used as a basis forthe determination refers to, for example, information about paper storedin each paper feed stage. A paper feed stage list 902 indicates thepaper feed stages set in the sheet feed unit 212 of the image processingapparatus 100 at the time when the user operates this UI.

FIG. 11 is a flowchart illustrating processing for generating anddisplaying the paper feed stage list 902. A control program for thisflowchart is stored in the ROM 206, and is loaded into the RAM 207 andexecuted by the CPU 201. The CPU 201 executes this processing at thetiming when the CALIBRATION SETTING screen 901 is displayed. In stepS1101, the CPU 201 acquires the paper feed stage information from thepaper feed stage information acquisition unit 511. In step S1102, theCPU 201 acquires the calibration paper registration information from thecalibration paper registration unit 509. In step S1103, the CPU 201generates the paper feed stage list 902 based on the informationacquired in steps S1101 and S1102. The information in the paper feedstage list 902 includes an item 903 indicating the name of each paperfeed stage, an item 904 indicating the size and type of set paper, andan item 905 indicating whether the each paper is registered ascalibration paper. In step S1104, the CPU 201 displays the paper feedstage list 902 generated in step S1103.

In the CALIBRATION SETTING screen 901, when the user selects any paperfeed stage and then press the EXECUTE button 908, the CPU 201 executescalibration by using the paper set in the selected paper feed stage. Thecalibration execution is controlled by the calibration control unit 508.Calibration processing will be described below. When the user pressesthe CANCEL button 909, the CPU 201 cancels the calibration setting, andchanges the screen to the main menu screen or the ADJUSTMENT/CLEANINGsetting screen 601. When the user presses the REGISTER PAPER button 907for performing the above-described calibration paper registration, theCPU 201 changes the screen to the CALIBRATION PAPER REGISTRATION screen801.

The following describes processing performed when the user presses theSELECT AUTOMATICALLY button 906, in which the present exemplaryembodiment is characterized. FIG. 10 illustrates an example of a UIscreen for executing calibration according to the present exemplaryembodiment. When the user presses the SELECT AUTOMATICALLY button 906,the CPU 201 displays a CALIBRATION EXECUTION screen 1001 on theoperation unit 204. The CPU 201 displays in the CALIBRATION EXECUTIONscreen 1001 a calibration execution list 1002 indicating a schedule ofthe calibration execution. The calibration execution list 1002 is a listof paper types enabling the generation of a correspondent correctiontable through the calibration execution. This list is generated by thecalibration execution list generation unit 507.

FIG. 12 is a flowchart illustrating processing for generating anddisplaying the calibration execution list 1002 via the calibrationexecution list generation unit 507. A control program for this flowchartis stored in the ROM 206, and is loaded into the RAM 207 and executed bythe CPU 201. This processing is executed at the timing when theCALIBRATION SETTING screen 901 is displayed. Processing in steps S1201and S1202 is similar to processing in steps S1101 and S1102,respectively. In step S1201, the paper feed stage informationacquisition unit 511 acquires the paper feed stage information. In stepS1202, the calibration paper registration unit 509 acquires thecalibration paper registration information. In step S1203, the print jobinformation acquisition unit 406 acquires print job information. Whenthe CPU 201 of the image processing apparatus 100 sends an inquiry tothe CPU 301 of the print server 102, the CPU 301 acquires a print joblist existing in the standby queue 405 via the print job informationacquisition unit 406. The above-described print job information acquiredincludes at least the job number and paper information indicating apaper type specified to be used at the time of each job execution, outof information set in all of print jobs stored in the standby queue 405in the HDD 306.

In step S1204, the CPU 201 generates the calibration execution list 1002based on the paper feed stage information acquired in step S1201, thecalibration paper registration information acquired in step S1202, andthe print job information acquired in step S1203, by using a methoddescribed below. In step S1205, the CPU 201 displays the calibrationexecution list 1002 generated in step S1204.

FIG. 13 is a flowchart illustrating an example of processing forgenerating the calibration execution list 1002 in step S1204. A controlprogram for this flowchart is stored in the ROM 206, and is loaded intothe RAM 207 and executed by the CPU 201. In step S1301, based on theprint job information, the CPU 201 selects a print job having the jobnumber 1 which is to be executed first when printing is started, andacquires paper information indicating a paper type specified to be usedat the time of the relevant job execution. In step S1302, the CPU 201compares the selected paper type with the paper feed stage informationto determine whether paper of the selected paper type exists in any oneof the paper feed stages. When paper of the selected paper is determinedto exist in any one of the paper feed stages (YES in step S1302), theprocessing proceeds to step S1303. Otherwise, when the selected paper isdetermined to not exist in the paper feed stages (NO in step S1302), theprocessing proceeds to step S1305. In step S1303, the CPU 201 comparespaper of the selected paper type with the calibration paper registrationinformation to determine whether the paper type specified to be used atthe time of execution of the selected job is registered as calibrationpaper. When the selected paper type is determined to have beenregistered (YES in step S1303), the processing proceeds to step S1304.Otherwise, when the selected paper type is determined to have not beenregistered (NO in step S1303), the processing proceeds to step S1305. Instep S1304, the CPU 201 appends the paper type specified to be used atthe time of execution of the selected job to the calibration executionlist 1002. The CPU 201 performs this processing because it determinesthat the paper type specified to be used at the time of execution of theselected job exists in any one of the paper feed stages, and thatcalibration can be executed when the relevant paper type is registeredas calibration paper. In step S1305, the CPU 201 determines whether anyjob has not yet been selected from the print job information. When anyjob is determined to have not yet been selected (YES in step S1305), theprocessing proceeds to step S1306. In step S1306, the CPU 201 selects apaper type specified to be used at the time of execution of the job nothaving been selected out of standby print jobs, and the processingproceeds to step S1302. When all of standby print jobs are determined tohave been processed for each paper type specified to be used at the timeof job execution (NO in step S1305), the processing exits thisflowchart. With the above-described processing, the CPU 201 selects allof paper types enabling the generation of a correspondent correctiontable through the calibration execution, and displays them in thecalibration execution list 1002.

As illustrated in the calibration execution list 1002, when the usersequentially selects paper types specified to be used at the time of jobexecution in order from the job number 1, the CPU 201 generates a listof calibration execution for generating a correspondent correction tablein order of paper types used in print jobs. If the user wants to changethe execution order of calibration or if the user does not want toexecute calibration for certain paper, the user can change the relevantsetting by using buttons 1007 to 1009 at right. When the user pressesthe UP button 1007 with any paper type selected in the calibrationexecution list 1002, the selected paper type is moved up to the upperrow. Likewise, when the user presses the DOWN button 1008, the selectedpaper type is moved down to the lower row. When the user presses theDELETE button 1009, the selected paper type is deleted from thecalibration execution list 1002.

When the user presses an EXECUTE button 1010, the CPU 201 transmits thecalibration execution list 1002 to the calibration control unit 508. Thecalibration control unit 508 sequentially executes calibrationprocessing based on the received calibration execution list 1002. Whenthe user presses a CANCEL button 1011, the CPU 201 changes the screenfrom the CALIBRATION EXECUTION screen 1001 to the CALIBRATION SETTINGscreen 901.

The following describes calibration execution processing with referenceto FIG. 14 to FIGS. 16A and 16B. The calibration execution processing isexecuted by the calibration control unit 508. FIG. 16A is a graphillustrating a relation between gradation data to be corrected bycalibration processing and target gradation. FIG. 16B is a graphillustrating a relation between the target gradation and correction datato be generated.

FIG. 14 is a flowchart illustrating an example of calibration executionprocessed by the calibration control unit 508.

A control program for this flowchart is stored in the ROM 206, and isloaded into the RAM 207 and executed by the CPU 201. This processing isexecuted when the user presses the EXECUTE button 908 in the CALIBRATIONSETTING screen 901, or when the user presses the EXECUTE button 1010 inthe CALIBRATION EXECUTION screen 1001. In step S1401, the CPU 201selects the first calibration set stored in the calibration executionlist 1002. In step S1402, the CPU 201 executes calibration processing(described below). In step S1403, the CPU 201 determines whether thefollowing calibration set exists in the calibration execution list 1002.When the following set is determined to exist (YES in step S1403), thenin step S1404, the CPU 201 selects the calibration set. Then, in stepS1402, the CPU 201 executes calibration for the calibration set. Whenall of the calibration sets in the calibration execution list 1002 havebeen executed (NO in step S1403), the processing exits this flowchart(the calibration execution processing ends). The print job is executedafter completion of generation of a correction table corresponding toeach paper type set in each print job included in the print job list inthis way, i.e., after completion of the calibration execution.

FIG. 15 is a flowchart illustrating an example of processing for thecalibration execution in step S1402. A control program for thisflowchart is stored in the ROM 206, and is loaded into the RAM 207 andexecuted by the CPU 201. In step S1501, the CPU 201 prints out acalibration chart image. Calibration chart image data is prestored inthe HDD 208. A calibration chart image is formed based on this data, andis printed on paper. Generally, a calibration chart image is formed ofthe necessary number of patch images arranged to generate reproductioncharacteristics data for the printer unit 209. In step S1502, the CPU201 loads the calibration chart image. The image processing apparatus100 according to the present exemplary embodiment includes themeasurement unit 214 in the printer unit 209. The measurement unit 214includes the sensor 215 disposed on the paper conveyance path betweenthe fixing unit and the sheet discharge unit 213. The sensor 215 refersto, for example, a measurement sensor capable of reading the density andchromaticity of patch images printed on paper. The sensor 215sequentially reads the printed patch images one by one to generatereproduction characteristics data. Gradation characteristics data, oneof reproduction characteristics data, refers to, for example, the readgradation data illustrated in FIG. 16A, and is generated as a LUT forassociating the input signal value with the output density. In stepS1503, the CPU 201 generates correction data.

When the reproduction characteristics data is gradation characteristicsdata, the correction data refers to, for example, the density gradationcorrection data (correction LUT) illustrated in FIG. 16B. The relationbetween FIG. 16B and FIG. 16A is indicated by an LUT for converting theinput signal value into the output signal value so that the readgradation (reproduction characteristics) coincides with the targetvalue. In step S1504, the CPU 201 stores the generated correction LUT inthe HDD 208, and the processing exits the flowchart.

Data of the correction LUT is stored for each paper type (calibrationset). When the CPU 201 executes a print job, the CPU 201 selects acorrection LUT based on the paper information set for the print job.Then, the calibration correction application unit 503 utilizes thecorrection LUT to apply correction to the print job to be output.

Although, in the present exemplary embodiment, calibration forcorrecting the gradation characteristics has specifically beendescribed, calibration is not limited thereto. The color reproductioncharacteristics represented by mixed-color may be corrected. Mixed-colormeans a color produced by a plurality of toners. For example, the red,green, and blue colors are respectively produced by using two out of theC, M, and Y colors. The gray color is produced by using the C, M, and Ycolors. When correcting the monochromatic gradation characteristics, theCPU 201 uses a one-dimensional LUT as a target value. However, whencorrecting the color characteristics with mixed-color, the CPU 201 usesa multi-dimensional LUT as a target value.

Thus, in the present exemplary embodiment, at the time of calibrationexecution, the CPU 201 can acquire information about a paper type to beused for execution of an input print job, and execute calibration on thepaper type requiring the generation of a correction LUT.

Thus, before execution of a print job, the CPU 201 can selectivelyexecute calibration on each paper type requiring the generation of acorrection LUT. This enables reducing useless consumption at the time ofcalibration execution.

The CPU 201 presents calibration to be selectively executed to the user,allowing the user to further determine whether calibration is to beexecuted or not and the execution order of calibration. Thus, even ifthe user does not have in-depth knowledge of calibration, the user caneasily operate calibration which needs to be executed.

In the first exemplary embodiment, the CPU 201 extracts only paper typesstored in the paper feed stages, having a registered target value, outof paper types specified to be used for execution of print jobs,executes calibration, generates the calibration execution list 1002, anddisplays it on the UI screen 1001.

In a second exemplary embodiment, it is considered that the CPU 201presents paper types not enabling the calibration execution out of papertypes specified to be used for execution of print jobs to the user.

FIG. 17 illustrates a UI of an example of a list of paper types notenabling the calibration execution and the generation of a correspondentcorrection table according to the second exemplary embodiment. This UIis processed by the CPU 201, and displayed, for example, on theCALIBRATION EXECUTION screen 1001. Alternatively, it is also possible toarrange a warning message and a button in the CALIBRATION EXECUTIONscreen 1001, and, when the user presses the button, display the UI asanother screen. The UI includes an item 1701 indicating the job number,and an item 1702 indicating paper information set in each job. The UIfurther includes an item 1703 indicating information about each paperfeed stage in which the relevant paper is set. If the relevant paper isset (stored) in none of the paper feed stages, a message, such as“UNSET”, is displayed to notify the relevant condition. The UI furtherincludes an item 1704 indicating information about whether the relevantpaper is registered as calibration paper. If no paper is registered asregistration paper, a message, such as “UNREGISTERED”, is displayed tonotify the relevant condition. An item 1705 indicates messageinformation to be presented to the user, which indicates an actionrequired to be performed next to enable the calibration execution.

According to the second exemplary embodiment, the CPU 201 can presentpaper types not enabling the execution of calibration for generating acorrection table at present.

Accordingly, out of print jobs subjected to printing stored in thestandby queue 405, the user can easily identify paper types notinvolving the generation of a correction table, and possibly notsubjected to suitable correction on a print product to be output. Bynotifying the user of paper types not involving the generation of asuitable correction table before execution of a print job in this way,it becomes possible to prevent output of a low-image-quality printproduct not involving the suitable generation of a correction table, andnot subjected to suitable correction.

In a third exemplary embodiment, conditions for determining the order ofselection and execution of calibration sets in the calibration executionlist 1002. Further, in the third exemplary embodiment, the CPU 201 setsan effective period to calibration sets.

FIG. 18 illustrates a UI of an example of a CALIBRATION EXECUTION(AUTOMATIC SELECTION SETTING) screen 1801 according to the thirdexemplary embodiment. This UI is processed by the CPU 201 via thecalibration execution list generation unit 507. When the user pressesthe SELECT AUTOMATICALLY button 906 in the CALIBRATION SETTING screen901, the CALIBRATION EXECUTION (AUTOMATIC SELECTION SETTING) screen 1801is displayed on the operation unit 204.

The following describes two different methods for selecting paper typesinvolving the generation of a correspondent correction table.

The first method is to select paper types from print jobs in the standbyqueue 405 described in the first exemplary embodiment. The second methodis to select paper types enabling execution of calibration forgenerating a correspondent correction table (the second method is togenerate a correction table for paper types having a target value)regardless of print jobs in the standby queue 405. A check box 1802 isused to specify selection of paper types from print jobs in the standbyqueue 405. Check boxes 1803 to 1805 are used to specify conditions fordetermining the execution order of calibration on the selected papertypes. A check box 1803 is used to specify generation of the calibrationexecution list 1002 in execution order of print jobs stored in thestandby queue 405. A check box 1804 is used to specify generation of thecalibration execution list 1002 in descending order of the calibrationexecution time (time taken for the calibration execution), i.e.,starting with a calibration set requiring the longest time ofcalibration processing. A check box 1805 is used to specify generationof the calibration execution list 1002 in ascending order of thecalibration execution time, i.e., starting with a calibration setrequiring the shortest time of calibration processing. A check box 1806is used to specify selection of all of executable calibration setsregardless of whether a print job exists in the standby queue 405. Thecalibration execution list 1002 is generated according to the checkboxes pressed by the user, and calibration is executed based on thegenerated list.

The following describes the calibration time. The calibration timediffers according to the printing performance of the image forming unit210 of the image processing apparatus 100, and depends on the type ofthe target paper (paper type). Generally, printing on paper having alarger grammage (paper type classification) takes a longer time. Thecalibration time also depends on the number of calibration chart imagesheets output in step S1501 in calibration processing.

When reading patch images formed on a printed chart image by using thesensor 215 in the measurement unit 214 of the printer unit 209 in stepS1502, a chart image printed on paper having a large grammage will beheated to high temperature after fixing. Therefore, to lower the papertemperature before measurement, it is necessary to provide a wait timebetween fixing and measurement by the sensor 215. This measures is takento cope with the change in tint and density of the patch images due tothe paper temperature, which is generally referred to as thermochromismphenomenon. If the sensor 215 reads density information of the patchimages on the chart image printed on paper at high temperature, the readdensity will be different from the density as a result of measuringpatch images on a chart image printed on paper at the room temperature.Thus, the accuracy of correction applied to a print product willdecrease. To avoid this, after printing and fixing on paper having alarge grammage, the CPU 201 waits for a while or reduces the conveyancespeed during conveyance inside the engine until the paper temperaturefalls to the room temperature, and then starts measurement via thesensor 215.

Calibration for generating a correction table corresponding to a papertype requiring measures for preventing the influence of thermochromismmay take an extremely longer time than calibration on a paper type notrequiring consideration of the influence of thermochromism.

Information about calibration time for generating a correction tablecorresponding to paper types requiring measures for preventing theinfluence of thermochromism is prestored in the HDD 208. In the presentexemplary embodiment, the calibration paper registration unit 509determines the calibration time stored in the HDD 208 based onregistered paper types, and stores the calibration time in an associatedway as one piece of the calibration paper registration information.

Further, the third exemplary embodiment sets information about aneffective period for correction for each paper type, considers provisionof an effective period for calibration. When the user inputs any timeduration as an effective period for calibration on a UI (notillustrated), effective period information is set. When the user checksa check box 1807, a paper type determined to have undergone thecalibration execution within the effective period will not be appendedto the calibration execution list 1002. Specifically, the CPU 201 doesnot execute calibration for generating a correction table correspondingto the relevant paper type. This is because, within the effectiveperiod, the image characteristics of the image forming unit 210 do notchange so much and therefore re-execution of calibration is thought tobe unnecessary. Successively using the last generated correction table(correction result) enables preventing redundant calibration execution.When the user presses an OK button 1808, the CPU 201 generates thecalibration execution list 1002 based on set conditions, changes thescreen to the CALIBRATION EXECUTION screen 1001, and displays thecalibration execution list 1002. Then, based on the generatedcalibration execution list 1002, the CPU 201 determines the executionorder of calibration by the calibration control unit 508. In steps S1401and S1404, in the determined calibration order, the CPU 201 selects apaper type involving the generation of a correspondent correction table,and a registered value defined for the paper type. When the user pressesthe CANCEL button 1809, the CPU 201 cancels the processing and thenchanges the screen to the CALIBRATION SETTING screen 901 or the mainmenu screen.

FIG. 19 illustrates an example of a UI indicating the calibration paperregistration information according to the third exemplary embodiment.This UI is processed by the CPU 201 via the calibration paperregistration unit 509, and then displayed on the CALIBRATION PAPERREGISTRATION screen 801. The UI includes an item 1901 indicating thename of paper (paper type), and an item 1902 indicating the date andtime when the paper was registered, which are equivalent to the items802 and 803, respectively. The UI further includes an item 1903indicating the date and time when calibration was executed last (acorrection table was generated). The UI further includes an item 1904indicating the reference time duration required to execute calibration.These pieces of information are stored in the HDD 208 as the calibrationpaper registration information.

The following describes the transition of UI screens displayed on theoperation unit 204 of the image processing apparatus 100 according tothe third exemplary embodiment, with reference to FIG. 20. Data of theUI screens is stored in the ROM 206, read by the CPU 201, and displayedon the operation unit 204. A UI screen 2001 is a main menu screen (notillustrated). All of operations to be made on the image processingapparatus 100 can be activated from the main menu screen 2001. A UIscreen 2002 is a copy setting screen (not illustrated). Scan and sendsetting screens (not illustrated) may exist in FIG. 20. A UI screen 2003is a paper setting screen. When the user presses a paper setting buttonin the main menu screen 2001, the CPU 201 displays the PAPER SETTINGscreen 701. When the user presses an adjustment/cleaning button in themain menu, the CPU 201 displays an adjustment/cleaning screen 2004, forexample, the ADJUSTMENT/CLEANING setting screen 601 on the operationunit 204. The adjustment/cleaning screen 2004 displays selection itemsfor the adjustment function of the image processing apparatus 100, suchas items for calibration setting and calibration paper registration. AUI screen 2005 is a calibration setting screen. When the user pressesthe UI button 603 in the adjustment/cleaning screen 2004, the CPU 201displays the CALIBRATION SETTING screen 901 on the operation unit 204. AUI screen 2006 is a calibration paper registration screen. When the userpresses the calibration paper registration button 605 in theADJUSTMENT/CLEANING setting screen 601 or the REGISTER PAPER button 907in the CALIBRATION SETTING screen 901, the CPU 201 displays theCALIBRATION PAPER REGISTRATION screen 801 on the operation unit 204. AUI screen 2007 is a calibration execution (automatic selection setting)screen 2007. When the user presses the SELECT AUTOMATICALLY button 906in the CALIBRATION SETTING screen 901, the CPU 201 displays theCALIBRATION EXECUTION (AUTOMATIC SELECTION SETTING) screen 1801 forsetting conditions for generating the calibration execution list 1002 onthe operation unit 204. A UI screen 2008 is a calibration executionscreen. When the user presses the OK button 1808 in the CALIBRATIONEXECUTION (AUTOMATIC SELECTION SETTING) screen 1801, the CPU 201displays the CALIBRATION EXECUTION screen 1001 on the operation unit204. The CPU 201 displays the calibration execution list 1002 generatedaccording to each condition. When the user presses the EXECUTE button1010, the CPU 201 executes calibration processing, and displays the mainmenu screen 2001 on the operation unit 204.

According to the third exemplary embodiment, after calibrationexecution, the CPU 201 can generate the calibration execution list 1002in consideration of selection of paper types involving the generation ofa correspondent correction table and the execution order of calibration.Thus, it becomes possible to freely generate the calibration executionlist 1002 according to user's preferences simply by selecting specificconditions. It is also possible to set an effective period forcalibration, and change conditions not to include in the calibrationexecution list 1002 paper types having undergone the generation of acorrespondent correction table through the calibration execution withinthe effective period.

Specifically, it becomes possible to perform control not to executeunnecessary calibration.

A fourth exemplary embodiment enables setting a timing of executingcalibration for generating a correction table to paper types in thegenerated calibration execution list 1002.

In the above-described exemplary embodiments, it is possible tocontinuously execute calibration for generating a correction tablecorresponding to each of a plurality of paper types. However, asituation can be assumed where there is a paper type not requiring thegeneration of a correspondent correction table by immediately executingcalibration. For example, a situation is assumed where the user wants toexecute calibration only on a print job required to be urgently printed,and, after completion of printing of the relevant print job, to executecalibration and printing on the remaining print jobs.

FIG. 21 illustrates a UI of an example of the calibration execution list1002 according to the fourth exemplary embodiment. This UI is processedby the CPU 201 via the calibration execution list generation unit 507,and is displayed on the calibration execution list 1002. Items 2101 to2104 are similar to items 1003 to 1006, respectively, and redundantdescriptions thereof will be omitted.

The UI includes an item 2105 indicating the timing of calibrationexecution for each paper type.

Two different timings of calibration execution can be set. The firsttiming is a timing 2106. Calibration is executed after the EXECUTEbutton 1010 is pressed before the first print job is started. The secondtiming is a timing 2107. Calibration is executed during print jobexecution, i.e., immediately before execution of a print job for which apaper type specified in a calibration set is specified to be used.

When the user selects any calibration set and selects an item 2106(PROMPTLY) or an item 2107 (IMMEDIATELY BEFORE JOB) in the EXECUTIONTIMING column 2105 in the CALIBRATION EXECUTION screen 1001, the CPU 201sets the execution timing.

For a paper type for which “PROMPTLY” is selected, when the user pressesthe EXECUTE button 1010, the CPU 201 starts the calibration executionbefore executing the print job to be executed first out of input printjobs. In this calibration, the CPU 201 transmits an executioninstruction to the calibration control unit 508, and calibration isexecuted in the order specified in the calibration execution list 1002.

For a paper type for which “IMMEDIATELY BEFORE JOB” is selected, the CPU201 temporarily stores the paper type via the calibration setting unit506.

When the print data receiving unit 501 receives print data, the CPU 201compares the received print job number with the job number for the papertype temporarily stored. When the two job numbers coincide with eachother, the CPU 201 interrupts the print processing of the print job,transmits the relevant paper type to the calibration control unit 508,and executes calibration.

Specifically, the CPU 201 executes calibration during execution of inputprint jobs. Immediately before execution of a print job by using aspecified paper type, the CPU 201 executes calibration for generating acorrection table for the same paper type as the one to be used in therelevant print job.

According to the fourth exemplary embodiment, it is possible to selectan execution timing of calibration for generating a correspondentcorrection table for each paper type. Thus, the CPU 201 can flexibly seta timing of calibration execution depending on the user's printingsituation. By presetting a calibration execution timing for all of papertypes in this way, accurate calibration processing at a suitable timingcan be achieved even if the user does not stay around the imageprocessing apparatus 100.

Although the above-described exemplary embodiments have specificallybeen described based on an electrophotographic apparatus, the imageprocessing apparatus is not limited thereto, and may be an ink jetprinter and a thermal printer. The spirit of the present invention isnot limited to the printer type. Although the above-described exemplaryembodiments have specifically been described based on the use of tonerin electrophotographic printing as a recording agent, the recordingagent used for printing is not limited to toner, and may be otherrecording agents, such as ink. The spirit of the present invention isnot limited to the recording agent type.

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2012-278322 filed Dec. 20, 2012, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image processing apparatus comprising: anacquisition unit configured to acquire a paper type to be used at thetime of execution of an input print job; a determination unit configuredto determine a paper type to be used for executing the input print jobby using information about the paper type acquired by the acquisitionunit; and a generation unit configured to generate a correction tablecorresponding to the paper type determined by the determination unit,the correction table being used to correct an image that is formed by animage forming unit by using a value obtained as a result of measuring apatch formed by the image forming unit on paper of the paper typedetermined by the determination unit wherein the generation unitacquires an order of execution of print jobs from print job informationacquired by a print job information acquisition unit, and generatescorrection tables corresponding to paper types in the order of executionof print jobs.
 2. The image processing apparatus according to claim 1,further comprising a display unit configured to display a calibrationexecution list indicating paper types for which correction tables aregenerated by the generation unit.
 3. The image processing apparatusaccording to claim 1, further comprising a registration unit configuredto register a target value for each paper type, the target value beingused in correcting the image that is formed by the image forming unit,wherein, when a target value corresponding to the paper type determinedby the determination unit is not registered, a correction table is notgenerated by the generation unit.
 4. The image processing apparatusaccording to claim 1, further comprising a unit configured to determinean order of generation of correction tables to be generated by thegeneration unit.
 5. The image processing apparatus according to claim 1,further comprising an effective period information setting unitconfigured to set information about an effective period for thecorrection table generated by the generation unit, wherein, for a papertype for which a correction table is generated within the effectiveperiod set by the effective period information setting unit, a newcorrection table is not generated by the generation unit.
 6. The imageprocessing apparatus according to claim 1, wherein the generation unitdetermines an order of generation of correction tables based on a timeduration required to generate a correction table corresponding to eachpaper type.
 7. The image processing apparatus according to claim 1,wherein, when the generation unit generates a correction table, ameasurement unit disposed on a paper conveyance path between a fixingunit and a sheet discharge unit measures a chart formed by using thepaper type to be used for executing the input print job.
 8. A method ofcontrolling an image processing apparatus having an image forming unitcomprising: acquiring a paper type to be used at the time of executionof an input print job; determining a paper type to be used for executingthe input print job by using information about the acquired paper type;acquiring an order of execution of print jobs; and generating acorrection table corresponding to the determined paper type, thecorrection table being used to correct an image that is formed by theimage forming unit by using a value obtained as a result of measuring apatch formed by the image forming unit on paper of the determined papertype, wherein the correction table corresponding to the determined papertype is generated in the acquired order of execution of print jobs.
 9. Anon-transitory computer-readable storage medium storing a program thatcauses a computer to execute the image processing method according toclaim 8.